In 1500 ce, from Paris to Beijing, the bulk of the world's population was governed by clerics and emperors. In Latin Christendom, the dream of reuniting Europe under the imperial sceptre continued to fire the hearts of men such as Charles V, while the pope remained unchallenged as Christendom's supreme spiritual leader. Throughout the Muslim world, the umma's seemingly unstoppable expansion looked set to continue, with the sixteenth century witnessing both the waxing of Ottoman power and the emergence of new Muslim empires in Safavid Iran and Mughal India. Finally, in the Far East, a far-flung suzerain state system flourished under the Ming dynasty, with the Chinese emperor exercising unchallenged regional hegemony by dint of his status as the Son of Heaven. Throughout the Old World, the ethical power of transcendental religious visions intertwined uneasily with the coercive power of dynastic empires. Faith and empire formed the twin foundations of regional international orders in Christendom, the umma and the Sinosphere, with the stability afforded by each facilitating the ensuing global demographic and commercial expansion that heralded the advent of modernity.

In the twenty-first century, emancipation has displaced salvation as the animating purpose of collective association, while the nation-state has eclipsed empire as the world's dominant form of political community. In the preceding chapters, I have sought to chronicle this transition, concentrating on two configurative crises that propelled the state system's genesis and expansion, before then considering the contemporary challenges that now threaten its untroubled perpetuation.